New geochemical data of the hydrothermal alteration zones associated with gold-bearing quartz veins at Atud mine are used for better understanding the ore evolution and exploration vectoring. ASTER and Landsat 8 OLI data are used to elucidate the distribution of gold-associated alteration zones. Three alteration zones are defined; zone 1 (sericite-kaolinite-quartz-pyrite), zone 2 (quartz-sericite-albite-pyrite), and zone 3 (chlorite-carbonate-epidote ± pyrite). Sericite and hydrothermal quartz are confined to the mineralized quartz veins. Fe-OH and OH-bearing minerals are observed along NW- and NE-trending shear zones in the Main Atud mine. The association of gold-bearing quartz veins and sericite alteration is constrained by processing ASTER- and OLI-imagery data. The geochemical data of the ore-enveloping hydrothermally altered rocks are used to assess the behavior of the REEs during the mineralization process. Mild enrichment in LREE and significant enrichment in the HREE are associated with sericite in zones (1) and (2) alterations. Carbonate alteration (zone 3) is enriched in LREE and in immobile HREE. Moreover, LREE and Eu anomalies have negative correlated with the Alteration Index (A.I.) and K2O index (K.I.) in zones 1 and 2, suggesting high mobility of LREE in K-rich hydrothermal fluids. On the other hand, HREE anomalies with increasing MgO index (M.I.) in alteration zone 3 may imply low solubility of these elements in alkaline solutions. Au anomalies linked to sericite/silica alteration is a rather meaningful vector for further exploration in the area.

Fault scarps that extend up to 155 km and have offsets of tens of meters at the surface are present in the northern parts of Finland, Norway and Sweden. These fault scarps are inferred to have formed during earthquakes with magnitudes up to 8 at the time of the last deglaciation. The Pärvie fault system represents the largest earthquake so far documented in northern Scandinavia, both in terms of its length and its calculated magnitude. It is also the longest known glacially induced fault in the world. Present-day microearthquakes occur along the length of the fault scarp on the eastern side of the scarp, in general agreement with an east dipping main fault. In the central section of the fault, where there is a number of subsidiary faults east of the main fault, it has been unclear how the earthquakes relate to the faults mapped at the surface. A seismic profile across the Pärvie Fault system acquired in 2007, with a mechanical hammer as a source, showed a good correlation between the surface mapped faults and moderate to steeply dipping reflectors. The most pronounced reflector could be mapped to about 3 km depth. In an attempt to map the fault system to deeper levels, a new 22 km long 2-D seismic profile which followed the 2007 line was acquired in June 2014. For deeper penetration an explosive source with a maximum charge size of 8.34 kg in 20 m deep shot holes was used. Reflectors can now be traced to deeper levels with the main 65◦ east dipping fault interpreted as a weakly reflective structure. As in the previous profile, there is a pronounced strongly reflective 60◦ west dipping structure present to the east of the main fault that can now be mapped to about 8 km depth. Extrapolations of the main and subsidiary faults converge at a depth of about 11.5 km where current earthquake activity is concentrated, suggesting their intersection has created favorable conditions for seismic stress release. Based on the present and previous seismic reflection data, potential locations for future boreholes for drilling into the fault system are proposed.

The objectives of the project are to develop a methodology for environmentally safe mine closure under specific conditions in the Barents region by cross border cooperation, exchange experiences and scientific knowledge.

The generation of acid mine drainage (AMD) from oxidation of sulphide- bearing waste is a world wide problem, due to low pH levels and the release of metals to recipients. It is therefore important to understand the fundamental geochemical processes occurring in mine waste. The geochemistry of the drainage water from the tailings at the abandoned Laver copper mine in Northern Sweden was studied in 2001 and compared with a previous study performed in 1993. All drainage water is collected in a brook, which means that Laver is a favourable site for mass balance studies. The results show a decrease in the amount of sulphide-associated elements such as S, Cu and Zn in the drainage water, and an increase of the pH level. It has been suggested that this is due to the decrease in the sulphide oxidation rate in the tailings. Modelling the oxidation front movement using the shrinking core model gives similar results. This indicates that the sulphur transported in the drainage water could relatively well reflect the oxidation rate in the tailings. Oxygen sampling was also performed in 2001- 2002 to evaluate whether the flux of oxygen into the tailings was restricted by a vegetation cover. The results show that vegetation does not limit oxygen diffusion into the tailings. There is an atmospheric concentration throughout a profile through oxidised grass covered tailings during the whole sampling period. Oxygen concentrations at depths where sulphide oxidation occurs show seasonal variations, probably due to varying water saturation. Cemented layers were sampled at two locations in the Laver impoundment tailings, where they had been formed in spite of the low sulphide content and lack of carbonates. The aim of the study was to determine the effects of cemented layer formation on metal mobility in the tailings. The cementing agents are jarosite and Fe-oxyhydroxides. Arsenic is strongly enriched and somewhat higher concentrations of Pb, V, Mo and Hg, compared to those in unoxidised tailings, occur in these layers. Sequential extraction shows that these metals are mostly adsorbed/co-precipitated with crystalline iron oxyhydroxides. The enriched metals will probably be remobilised if changes towards more reducing conditions occur, for instance as a result of remediation of the tailings impoundment. An attempt was made to use LA-ICP-SMS to quantify the role of pyrite surfaces as scavengers of metals in oxidising mine tailings. Pyrite grains were collected from a profile through the pyrite-rich tailings at the Kristineberg mine in Northern Sweden. At each spot hit by the laser, the surface layer was analysed in the first shot, and a second shot on the same spot indicated the chemical composition of the pyrite immediately below. The crater diameter for a laser shot is known, and by estimating the crater depth and total pyrite surface, the total enrichment on pyrite grains was calculated. Results are presented for As, Cd, Co, Cu, Ni and Zn. The results clearly show that there is an enrichment of As, Cd, Cu and Zn on the pyrite surfaces below the oxidation front in the tailings, but not of Co and Ni. Arsenic is also enriched on the pyrite grains that survived in the oxidised zone. However, only 1.4 to 3.1% of the Cd and Zn released by sulphide oxidation in the oxidised zone had been enriched on the pyrite surfaces in the unoxidised tailings, but for As and Cu the corresponding figures are about 64 and 43%, respectively. The results should not be taken too literally but allow the conclusion that scavenging to pyrite surfaces is an important process for retention of As and Cu below the oxidation front in pyrite-rich tailings. Although only pyrite grains that appeared to be fresh, without surface coatings, were used in this study, the possibility of a thin layer of Fe-hydroxides occurring must be considered. Both adsorption to the pyrite directly, or to Fe-oxyhydroxides, may explain the enrichment of As, Cd, Cu and Zn on the pyrite surfaces, and, in the case of Cu, also replacement of Fe (II) by Cu(II) in pyrite.

Large quantities of sulphide-bearing mining wastes produced from ore processing are deposited throughout the world. Sulphide oxidation in the wastes may release acidic water with high concentrations of metals to the environment. Remediation strategies are usually site specific, since the physical and chemical properties of the wastes vary. Therefore, sulphide oxidation, oxygen diffusion and metal mobility in unoxidised and oxidised, remediated and unremediated wastes have been studied in the present work. The efficiency of different cover systems on unoxidised tailings from Kristineberg, were studied in pilot-scale test cells (5*5*3 m3)under field conditions. Clayey till, sewage sludge, apatite and Trisoplast were used as sealing layers and unspecified till as a protective cover. In one cell tailings were left uncovered. Unoxidised tailings in the test-cells in the initial stage after deposition showed relatively low sulphur release (600- 800 mg/l)in leachate waters, which probably was an effect of high moisture content in the tailings prior to deposition. Near-neutral pH found in the leachates was an effect of neutralisation by carbonate minerals present and lime (Ca(OH)2) added prior to deposition. Similar sulphur concentrations were found also in the uncovered tailings. The sulphide oxidation rate increased with time in the uncovered tailings, and decreased in the covered. The lowest oxygen concentrations were observed below the cover system with sewage sludge, which was the most effective barriar against oxygen in a short-term perspective. The oxygen fluxes through the clayey till and apatite layers were within the same magnitude and varied between 0.5 and 4 mole/year,m2. The Trisoplast layer seemed to have failed as a barrier against oxygen. Tailings studied at field scale at Laver and Kristineberg had oxidised for more than 50 years. The tailings at Kristineberg have high pyrite content (c.25% and 50%) and those at Laver have low grade of pyrrhotite (2-3%). The Laver tailings are unremediated, while at Kristineberg the tailings were remediated in 1996. The transport of metals in the drainage water at Laver decreased during a study period of 8 years. The transport of dissolved sulphur indicated a declining trend of sulphide oxidation rate in the tailings, which was confirmed by oxygen measurements in the tailings and weathering rate estimations. The decline was considered to be natural as a result of the increased distance that oxygen has to travel to reach unoxidised sulphide grains. The major part of the amounts of metals released by sulphide oxidation were secondarily retained in the tailings, and to a small extent in layers cemented by jarosite and Fe-(oxy)hydroxides. Sequential extraction of these layers showed that metals such as Cu and Pb were mostly associated with crystalline Fe-(oxy)hydroxides. Most important retention mechanism was, however, sorption onto minerals surfaces below the oxidation front. The studied Impoundment 1 at Kristineberg was remediated by two different methods; on one part a dry cover consisting of a sealing layer and a protective cover were applied, and the groundwater table was raised and a single dry cover applied on the other part. When the groundwater table was raised in oxidised tailings, secondarily retained metals such as Fe, Mg, Mn, S and Zn were remobilised resulting in increased concentrations in the groundwater. The concentrations declined with time, due to dilution by inflowing uncontaminated water. Decreased concentrations of Fe, Mg, Mn, S and Zn were observed also in the groundwater below the dry cover as the amount of percolating water decreased. The concentrations of trace elements such as Cd, Co, Cr, Cu, Ni and Pb were almost depleted in the groundwater, since these metals were retained within the tailings by mechanisms such as co-precipitation, precipitation and sorption. Analysis of pyrite grains by LA-ICP-SMS showed that pyrite surfaces were important for retention of As and Cu, in particular, but also for Cd and Zn. This study shows that the physico-chemical conditions expressed by pH and redox potential have a large impact on element mobility’s. For example, As was mobilised as a result of remediation, while the concentrations of most metals decreased in the drainage waters.

Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH 9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation

The purpose of this literature review is to summarize the recent research regarding geochemical and geotechnical stability of paste tailings, identify knowledge gaps and future research needs. The present study has been conducted by the Division of Geosciences and Environmental Engineering together with the Division of Mining and Geotechnical Engineering at Luleå University of Technology on behalf of Boliden Mineral, LKAB and Outotec.A survey conducted by MEND (Mine Environment Neutral Drainage) in 2006 on the environmental effects related to the use of paste tailings summarizes that only a few studies had been performed about long-term effects on the surface and groundwater quality. Instead, the focus had been on the additives and the strength of the paste. It is still uncertain how the paste technology affects the long-term environmental stability from a geochemical point of view. Concerns regarding the stability of paste with high sulphide content are still relevant. Studies performed indicate that sulphide oxidation occurs within cemented paste as well as on the surface of non-cemented paste and cracks formed on the surfaces could induce oxidation. For cemented paste, metals released by sulphide oxidation might be sequestered due to high pH induced by the alkaline additives, but anion such as Se has been shown to be mobilized. The leachate has been shown to be near-neutral initially, but the neutrality decreases with time and probably metals sequestered in the matrix will also be released. Again, it should be noted that no long term study was performed on leaching of paste, cemented or uncemented. The longest leaching study was performed for one year. Arsenic has been proven to be retained in Ca-arsenates in cemented paste, but the long term stability of these precipitates is relatively unknown. Expanded secondary phases e.g. gypsum and ettringite have been observed to form when there is sulphate in the process or drainage of water. These phases could crack the paste, but, on the other hand, can also fill former cracks when deposited in layers. The effects of the formation of these phases are relatively uncertain in a long-term perspective. Presence of different elements such as ammonium, sulphates and metals in the water has been shown to negatively affect the curing process and therefore water is suggested to be treated before use. The presence of carbon dioxide during the paste formation could also affect the curing process, but could sequester metals in carbonate phases.Geotechnical and rheological properties of paste is well defined and documented. Several case studies have been found in literature providing valuable information about the details of the works being carried out. However, a difficulty has been noted during the investigation of the effects of cold climate conditions when current practice is applied in the colder parts of the world. It is not certain how some specific and vital parameters are going to be affected by cold temperatures. Parameters such as deposition slopes and deposition scheme, strength development of the paste are expected to be responsive to cold climate conditions. There are predictions about which properties are going to be affected in what way, but there is also a need to establish a scientific base for discussion. These have been highlighted as research needs and information gaps at the end of the report.

Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.

At the Kristineberg mine in northern Sweden, sulphide-rich tailings left open for 50 years were remediated in 1996 by applying double dry cover on one part of an impoundment, and raised groundwater level combined with simple till cover on the other part. Groundwater pipes installed in the impoundment were sampled from 1998 during a period of 6 years. The results showed that the groundwater quality varied considerably in the impoundment, even under the same type of cover. Secondarily retained Fe, S, Mg, Mn and Z were remobilised when the groundwater was raised. In the part with raised groundwater level, the average concentration of Fe ranged from 2700 to 9000mg/l in 1998, and the range for S was 2200 to 7000mg/l. During 2003 the average concentrations had decreased and ranged between 150 and 900 mg/l for Fe and between 130 and 900 mg/l for S. The improvement of the water quality was caused by inflow of less contaminated groundwater and decreasing sulphide oxidation rate. The redox potential generally decreased and pH increased. The concentrations of Cd, Cu and Pb in groundwater decreased rather rapidly all over the impoundment after remediation. In areas with relatively high pH and low redox potential, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were almost depleted.

The efficiency of five cover systems to decrease oxygen intrusion into sulphide-rich tailings was studied in pilot-scale test cells (5x5x3 m(3)). The covers consisted of clayey till, sewage sludge, fine-grained apatite concentrate or Trisoplast (a mixture of a polymer, bentonite and tailings sand) as sealing layers and unspecified till as protective cover. In one reference cell, tailings were uncovered. Oxygen concentrations below the entire covers were highest below the Trisoplast and apatite layers, and lowest below the sewage sludge layer. Effective diffusion coefficients (D-eff) and oxygen fluxes were estimated in the covers with non-oxygen-consuming sealing layers (clayey till and apatite). For the protective covers the Deff ranged between E-09 and E-07 m(2)/s, and for the sealing layers between E-10 and E-09 m(2)/s, and for the entire covers between E-10 and E-08 m(2)/s. Seasonal variations in D-eff were larger within the covers than between the different cover systems. Oxygen fluxes through the entire covers with clayey till and apatite ranged between 0.2 and 4 mole m(2)/year, which was a reduction of more than 99% compared to uncovered dry tailings.

Min-North is a transnational project financed by the Interreg Nord program and coordinated by LTU. The project is a cooperation between Geological survey of Finland, GTK, Oulo University (Finland), The Arctic University of Norway, UiT and several (>17) small and large enterprises and mining companies in the northern region with expertise within geology, waste management, geophysics and geochemistry. The overall goal is to reduce the environmental impacts of mining in the northern regions by developing, evaluating, optimizing environmental techniques. In Sweden, geophysical and geochemical techniques will be integrated to develop a 4D model for tracing pollution transport in the mine waste, mine areas and in(to) the surroundings.

The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

Cemented layers (hardpans) are common in carbonate or sulphide-rich mine tailings and where pyrrhotite is the predominating Fe-sulphide. Laver, northern Sweden, is an abandoned Cu-mine where the tailings have low pyrrhotite content, almost no pyrite and no carbonates. Two cemented layers at different locations in the Laver tailings impoundment were investigated, with the aim to determine their effects on metal mobility. The cementing agents were mainly jarosite and Fe-oxyhydroxides in the layer formed where the tailings have a barren surface, whereas only Fe-oxyhydroxides were identified below grass-covered tailings surface. Arsenic was enriched in both layers which also exhibit high concentrations of Mo, V, Hg and Pb compared to unoxidised tailings. Sequential extraction indicates that these metals and As were mainly retained with crystalline Fe-oxides, and therefore potentially will be remobilised if the oxic conditions become more reducing, for instance as a result of remediation of the tailings impoundment.

Leachate water quality from covered and uncovered unoxidised sulphide-rich tailings in six pilot-scale (5x5x3 m3) test cells was monitored during 2004 and 2005. The covers consisted of a layer of clayey till, sewage sludge, apatite or Trisoplast (a commercial mixture of tailings, bentonite, and a polymer). All layers were protected by an unspecified till except in one reference cell, where the tailings were left open. All leachate waters showed near-neutral pH as a result of neutralization by calcite in the tailings and by Ca(OH)2 added prior to deposition. Average dissolved sulphur concentrations in the leachates were ≈ 600 mg L-1, except in the cell with sewage sludge (300 mg L-1). The source of sulphur was mainly pyrite oxidation, but residual sulphur probably remained from the enrichment process. The near-neutral pH favoured precipitation of metal-(oxy)hydroxides with subsequent removal of trace elements such as Cd, Cu and Pb (< 15 μg L-1) from the solutions. High concentrations of Co, Mn, Ni, and Zn were found in leachates from the apatite, Trisoplast, and uncovered tailings cells. High As concentrations were found in the leachates in the sewage sludge and clayey till cells. The lowest metal concentrations, redox potential, and highest pH were found in the sewage sludge cell. Decreased elemental metal concentrations during 2004 suggest improved performance over time.

One of the major aims with passive remediation of sulfide-bearing mine tailings is to minimize or exclude oxygen diffusion through the tailings and decrease the oxidation of sulfides. A vegetation cover could potentially decrease the oxygen flux by oxygen consumption during decay of organic matter. The abandoned Cu mine at Laver in northern Sweden has not been remediated except for establishment of vegetation, and this offers the opportunity to investigate the effect of a vegetation cover on tailings.Whole-year sampling of surface drainage water from the tailings impoundment was performed during 1993 and 2001. The release of metals was only 5-10 % of the estimated weathering rate in the tailings during 1993 because of secondary retainment within the tailings. Results from 2001 show decreasing concentrations of several elements and increasing pH, indicating decreasing oxidation rate.Pore-gas measurement in two vertical profiles shows that vegetation on the tailings has no effect as a barrier for oxygen diffusion in comparison with barren parts.Cemented layers, which have formed at various depths in the tailings, have decreased the flux of oxygen to deeper parts; this could be an explanation of the decreased oxidation rate. The different cemented layers in the tailings differ in chemical composition and physical characteristics. There are two major types, both of which both contain iron oxides and carbon. The origin of the carbon is possibly the vegetation cover. None of the cemented layers acts as a trap for heavy metals, but As is enriched.The effect of vegetation as a oxygen barrier is negligible, but vegetation could act as a source for organic matter that could increase aggregation of iron oxides and clay minerals, thereby enhancing the formation of cemented layers or increasing metal-organic complexes which decrease the mobility of metals.

Tailings containing pyrrhotite were deposited in an impoundment at a copper mine at Laver, Northern Sweden, which operated between 1936 and 1946. Since then the oxidation of sulphides has acidified recipient water courses and contaminated them with metals. Measurements from surface water sampled in 1993, 2001 and 2004-05 from a brook into which the tailing impoundment drains indicate that the amounts of sulphide-associated elements such as Cu, S and Zn released into the brook have decreased over time, while pH has increased. The mass transport of S in the brook during 1993 and 2001 corresponded well with the amount of S estimated to be released from the tailings by oxidation. Secondary precipitates such as covellite and gypsum, which can trap sulphur, were shown in earlier studies to be present in only low amounts. The annual release of elements from the tailings was estimated from the volume of tailings assumed to oxidise each year, which depends on movement of the oxidation front with time. The results indicate that the oxidation rate in the tailings has decreased over time, which may be due to the increased distance over which oxygen needs to diffuse to reach unoxidised sulphide grains, or their cores, in the tailings.

Industrial, agricultural and rural activities may result in pollution of watercourses with elevated trace metal concentrations and implications for water supply and ecosystem functioning. The concentration of the trace metals Fe, Mn, Zn, Co, Pb, Cu, and Cd in the water and clay fractions (<2μm) of the bank sediments of River Tigris in Baghdad city were determined. Dissolved trace metals concentrations were far below the upper permissible limits during 2012-2013. There was no consistent pattern between element concentrations and river discharge. Seasonal interrelations between water and sediments were most obvious for Fe that decreased in both environments with rising flows during autumn. Although independent of discharge, Mn in water and sediments often followed each other at all stations. Zinc, however, increased in the sediments and decreased in the water with discharge. The clay fractions were slightly to strongly enriched in trace metals with the gradient Co > Fe > Zn > Mn > Cu suggesting absorption of the metals on sediment substrate.

Treated waste water is normally used for irrigation purposes in countries suffering from water shortages to narrow the gap between supply and demand. The concept behind this is to save water consumed for agricultural activities, which consumes most of the water, for municipal and industrial uses. The Alsukhna area in Jordan is used to grow vegetables which are irrigated by treated wastewater. Surface and groundwater samples from the Zarqa region were analyzed for their major cations, anions and heavy metals. The impact of the treated waste water on the chemical components of vegetables was studied using Zn, Mn, Fe, Pb and Ni in sweet and hot pepper, tomato, cauliflower, cabbage, squash, cucumber and eggplant which were compared with similar vegetables irrigated by natural unpolluted water from the Mafraq region. The four metals, namely Zn, Fe, Pb, and Ni, had concentrations higher than in the reference vegetables by 3423%, 155%, 397%, 2949% and 289%, 187%, 211%, 214% fortomato and cauliflower, respectively. Sweet pepper was mainly influenced by an increased content of Fe, which was almost 180% higher than that in sweet pepper from the Mafraq region. Hot pepper had highly elevated concentrations of Ni (6980%) and Zn (419%), while squash demonstrated high Zn (207%) and Pb (666%). When all the heavy metals are considered, the most affected vegetable is the hot pepper with an average percent of heavy metals accumulation of 1559% while the least effected is cabbage at 116%.

The potential of utilizing a new form of chemical processing technology called SpinChem® Rotating Bed Reactor (RBR), in combination with different reactive materials, for the purpose of remediating multi-contaminated aquifers under changing environmental conditions, was investigated using laboratory studies and geochemical models. Four different reactive materials, or combinations thereof, were tested: heat-treated peat powder combined with zero-valent iron (ZVI); IronPeat, which consists of peat powder coated with a ferriferous hydrosol (FFH); and a powdered steel waste product. Results showed that the powdered steel waste was compatible with the technology while the peat-based sorbents were not. However, there were no indications that the kinetics of the sorption reactions increased. This was attributed to the fact that the rate-limiting steps, for the binding of the studied metal(loid)s onto iron oxide, are generally considered to be dependent on the later stages of the sorption process related to diffusion mechanisms and not to the rate of mass transfer through the bulk liquid phase, which is what primarily is increased through application of the SpinChem® RBR technology.

The Skellefte mining district in northern Sweden contains over 85 pyritic Zn-Cu-Au-Ag massive sulphide deposits. The Renstrom area, one of the most intensely mineralized parts of the Skellefte district, contains five zinc-and gold-rich deposits, three of which are confined to a specific continuous stratigraphic unit, the "Renstrom ore host unit". The great structural complexity of the area made it difficult to locate and follow the ore horizon to generate new exploration targets. A new study in the Kyrkvagen area, based on stratigraphic correlations, structural interpretations and lithogeochemical and geophysical data interpretation, revealed several NW-trending faults which separate five structural blocks. The rocks of the area could be characterized in terms of geochemistry, stratigraphy and their position in the hanging or footwall with respect to the ore horizon. Moreover, alteration patterns allowed predictions of possible extensions of the ore horizon. This increased knowledge of the Kyrkvagen area led to the identification of five new drilling targets for further exploration in one of Boliden's most important mining areas.

The links between volcanism and massive sulphide deposits are being studied as part of the "Global Volcanic-hosted Massive Sulphide (VMS) Project", which is IGCP project 502. Different types and settings of VMS deposit show different degrees of influence from volcanic or magmatic processes, with the most distinct genetic connection shown by some felsic-hosted deposits. These influences include:(1) Basin-wide volcano-tectonic events cause deposition of VMS on specific time-stratigraphic horizons. (2) With the exception of mid-ocean ridge settings, major VMS deposits are mainly associated with felsic volcanic rocks, even where felsic rocks form a minor component of the region. (3) Most VMS deposits form in proximal volcanic settings. (4) Most VMS deposits form at a particular stage in the evolution of their host volcanoes, typically late in the magmatic-hydrothermal cycle following a significant felsic eruptive event. The specific relationship in time and place implied by these last two points indicate that either the magmatic-hydrothermal cycle creates an important part of the ore solution, or controls when and where a metal-bearing geothermal solution can be focused and expelled to the sea floor, or both.(5) VMS deposits occur preferentially at times and places where both felsic and mafic magmas were erupted. In felsic-dominated regions, eruption of the mafic rocks commonly closely followed deposition of the ore-host felsic package. (6) Volcanic host rocks influence the morphology and stratigraphic position of VMS. Volcaniclastic and especially pumiceous strata promote deposition of VMS below the sea floor via replacement, whereas coherent lava flows and intrusions promote deposition of VMS on the sea floor. (7) Volcanic rocks and/or magmas are probably the source of metals in most VMS deposits.

Although volcanic-associated massive sulphide (VMS) deposits have been studied extensively, the geodynamic processes that control their genesis, location and timing remain poorly understood. Comparisons among major VMS districts, based on the same criteria, have been commenced in order to ascertain which are the key geological events that result in high-value deposits. The initial phase of this global project elicited information in a common format and brought together research teams to assess the critical factors and identify questions requiring further research. Some general conclusions have emerged. (1) All major VMS districts relate to major crustal extension resulting in graben subsidence, local or widespread deep marine conditions, and injection of mantle-derived mafic magma into the crust, commonly near convergent plate margins in a general back-arc setting. (2) Most of the world-class VMS districts have significant volumes of felsic volcanic rocks and are attributed to extension associated with evolved island arcs, island arcs with continental basement, continental margins, or thickened oceanic crust. (3) They occur in a part of the extensional province where peak extension was dramatic but short-lived (failed rifts). In almost all VMS districts, the time span for development of the major ore deposits is less than a few million years, regardless of the time span of the enclosing volcanic succession. (4) All of the major VMS districts show a coincidence of felsic and mafic volcanic rocks in the stratigraphic intervals that host the major ore deposits. However, it is not possible to generalize that specific magma compositions or affinities are preferentially related to major VMS deposits world-wide. (5) The main VMS ores are concentrated near the top of the major syn-rift felsic volcanic unit. They are commonly followed by a significant change in the pattern, composition and intensity of volcanism and sedimentation. (6) Most major VMS deposits are associated with proximal (near-vent) rhyolitic facies associations. In each district, deposits are often preferentially associated with a late stage in the evolution of a particular style of rhyolite volcano. (7) The chemistry of the footwall rocks appears to be the biggest control on the mineralogy of the ore deposits, although there may be some contribution from magmatic fluids. (8) Exhalites mark the ore horizon in some districts, but there is uncertainty about how to distinguish exhalites related to VMS from other exhalites and altered, bedded, fine grained tuffaceous rocks. (9) Most VMS districts have suffered fold-thrust belt type deformation, because they formed in short-lived extensional basins near plate margins, which become inverted and deformed during inevitable basin closure. (10) The specific timing and volcanic setting of many VMS deposits, suggest that either the felsic magmatic-hydrothermal cycle creates and focuses an important part of the ore solution, or that specific types of volcanism control when and where a metal-bearing geothermal solution can be focused and expelled to the sea floor, or both. This and other questions remain to be addressed in the next phase of the project. This will include in-depth accounts of VMS deposits and their regional setting and will focus on an integrated multi-disciplinary approach to determine how mineralisation, volcanic evolution and extensional tectonic evolution are interrelated in a number of world-class VMS districts.

Ferromanganese nodules from the Pacific and Atlantic Oceans, the Barents and Baltic Seas, and the Gulf of Bothnia were analyzed for the isotopic compositions of Ce, Nd and Sr and the abundances of REE, Ba and Sr. REE patterns of Barents, Baltic and Bothnian samples show no Ce anomaly, or even a negative one, in contrast to the positive anomaly observed for the Pacific and Atlantic samples. Moreover, the Baltic and Bothnian samples have distinctly low εNd values; average εNd values of the four regions are as follows: Pacific -5, Barents -10, Atlantic -11 and Baltic inclusive of Gulf of Bothnia -19. The characteristic low εNd values of the Baltic samples are indicative of the influence of Precambrian rocks from the Baltic shield. Of particular interest is the feature of the Ce isotopic composition that εCe values of the samples from the Pacific are negative and those from the other three regions positive. This novel finding might suggest a difference in sources of Ce between the Pacific and other regions. These results demonstrate that Ce isotopic ratios can be a useful tracer in marine geochemistry, in combination with isotopic compositions of Nd and Sr.

Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.

Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended

This ongoing project focusses on the structural evolution of the Per Geijer apatite iron ores in Kiruna, northern Sweden. The Per Geijer iron ores are situated in a NNE-SSW trending shear zone. This study indicate that the shear zone was active during D2 E-W compression giving rise to dip-slip and oblique slip components. The ductile fabric is overprinted by brittle structures carrying Cu, possibly representing traces of a separate Iron Oxide Copper Gold event in northern Norrbotten.

Variations in the physico-chemical speciation of the rare earth elements (REE) have been investigated in a subarctic boreal river during an intense spring flood event using prefiltered (<100 μm) samples, cross-flow (ultra)filtration (CFF), flow field-flow fractionation (FlFFF), and diffusive gradients in thin films (DGT). This combination of techniques has provided new information regarding the release and transport of the REE in river water. The colloidal material can be described in terms of two fractions dominated by carbon and iron, respectively. These two fractions, termed colloidal carrier phases, showed significant temporal changes in concentration and size distribution. Before the spring flood, colloidal carbon concentrations were low, the colloids being dominated by relatively large iron colloids. Colloidal concentrations increased sharply during the spring flood, with smaller carbon colloids dominating. Following the spring flood, colloidal concentrations decreased again, smaller carbon colloids still dominating. The REE are transported mainly in the particulate and colloidal phases. Before the spring flood, the REE composition of all measured fractions was similar to local till. During the spring flood, the REE concentrations in the colloidal and particulate fractions increased. The increase was most marked for the lighter REE, which therefore showed a strong enrichment when normalized to local till. Following the spring flood, the REE concentrations decreased again and reverted to a distribution similar to local till. These changes in the concentration and distributions of carbon iron and REE are interpreted in terms of changing hydrological flow paths in soil and bedrock which occur during the spring flood.